Table 1 Demographic data of children who returned screening questionnaire between years 2013 and 2016
| Â | Total (N = 3954) | |||
|---|---|---|---|---|
| Â | N | % | Mean | SD |
Sex | ||||
 Boys | 2022 | 51.1 |  |  |
 Girls | 1932 | 48.9 |  |  |
Age (months) | Â | Â | 62.7 | 3.2 |
Gestational age (weeks) | Â | Â | Â | Â |
 < 28 | 26 | 0.7 |  |  |
 28 < = < 37 | 397 | 10.0 |  |  |
 37 < = < 42 | 3388 | 85.7 |  |  |
 42 < = | 143 | 3.6 |  |  |
Birth weight (g) | ||||
 < 1000 | 12 | 0.3 |  |  |
 1000 < = < 1500 | 16 | 0.4 |  |  |
 1500 < = < 2500 | 349 | 8.8 |  |  |
 2500 < = < 4000 | 3531 | 89.3 |  |  |
 4000 < = | 46 | 1.2 |  |  |
Family structure | ||||
 living with parents | 3532 | 89.3 |  |  |
 living with a single parent | 376 | 9.5 |  |  |
 Others | 46 | 1.2 |  |  |
History of developmental abnormalities | 182 | 4.6 | Â | Â |
Familial annual income | ||||
 < JPY 2 million | 312 | 7.9 |  |  |
 JPY 2–4 million | 1242 | 31.4 |  |  |
 JPY 4–7 million | 1453 | 36.7 |  |  |
 JPY 7–10 million | 434 | 11.0 |  |  |
 JPY 10 million < = | 201 | 5.1 |  |  |